Two men are knocking back beers in a bar on the ninetieth floor of the Empire State building.
“You know, there’s a slipstream around the seventieth floor,” says one, opening a window, “and if you jump out here, it’ll suck you back in at the fiftieth floor.”

“Ah, c’mon,” says the second, more than a little drunk.
“No, really” says the first. “I’ll show you.” So he jumps out the window, comes in through a fiftieth-floor window, takes the elevator up, and appears triumphantly back in the bar.
“Hey, I’m going to try that,” says the second guy. He jumps out the window, falls ninety floors, and is killed instantly.
“Hey,” says the bartender, looking hard at the first man, “you can be a real bastard when you’re drunk, Superman.”